No connection to modem and single-board computer (Cubieboard)

Bebbi · November 21, 2022, 9:39pm

Good evening,
I'm using my OpenWRT router (IP: 192.168.2.1) behind a modem with the IP address 192.168.1.1. I cannot reach the modem for some time now. Becauce of I can get on the internet, it must be basically reachable. Furthermore I could reach my single board computer (Cubieboard) so far. Now this is not possible anymore. Normally I accessed my wiki via https://cubieboard2/wiki. It could be that it has the IP_address 192.168.2.145.

Do I have to create a route or something?

Thank you for your support.

Greetings

Bebbi

andyboeh · November 21, 2022, 9:46pm

How is the wan interface configured? You will probably need an interface so that the network is reachable - mine is called "modem" since the modem is reachable via its static IP 10.0.0.138. For my PPPoE WAN connection, I configured it as follows:

config interface 'modem'
	option proto 'static'
	option device 'br-lan.100'
	option ipaddr '10.0.0.1'
	option netmask '255.255.255.0'

config interface 'wan'
	option proto 'pppoe'
	option device 'br-lan.100'
	option username 'xxxx'
	option password 'xxxx'
	option ipv6 'auto'

Regarding your Cubieboard: Is it listed as a DHCP client on your OpenWrt installation? Does it work if you add .lan as domain name (as in cubieboard2.lan)?

Bebbi · November 21, 2022, 10:18pm

Hello,

I can't find "option ipaddr" and "option netmask " in "modem".

I have changed to "PPNoE" for WAN. This does nothing. It now shows "Connection attempt failed".

The ".lan" does not work either.

andyboeh · November 21, 2022, 10:40pm

Your WAN connection is a DHCP client, so accessing the 192.168.1.x subnet should work out of the box unless you changed the firewall configuration.
I'm on a PPPoE connection which does not have a network associated by default and I suspected you were maybe on PPPoE, too. Sorry for the noise.

Bebbi · November 21, 2022, 10:47pm

I have not changed anything in the firewall to my recollection.

andyboeh · November 21, 2022, 10:54pm

You added the MODEM interface just now (because I suggested it) and you deleted it in the meantime, right? Because I just found it on an older thread where you asked the same question (and were given about the same answers): Accessing the modem through the router - #8 by Bebbi

If this interface is active, it could explain why you can't access the router. So to sum up:

You only need:

LAN at 192.168.2.1/24
WAN as DHCP Client
WAN6 as DHCP6 Client

Bebbi · November 21, 2022, 11:25pm

No, "modem" was already there and I did not delete it. That I have dealt with it before, I completely forgot.

When I stop "modem", 192.168.1.1 correctly resolves to provider.box, but the interface is not accessible. http://192.168.2.154 still does not work.

Now I am at a loss and overwhelmed.

Bebbi · November 22, 2022, 12:12am

I followed your advice and deleted "modem". Now I reach the user interface of the modem again. But the URL provider.box does not work like before. But I still can't reach my single board computer.

I do not understand the use of the instructions now at all.

lleachii · November 22, 2022, 7:07am

Add that hostname to your OpenWrt device, pointing to the modem's IP.

moeller0 · November 22, 2022, 7:29am

Try getting a packet capture when you make a connection attempt and then look at the TTL field of packets coming from the modem.
Some network appliances set TTL to 1 so that they appear reachable only in the same L2 domain and not from behind a router.

andyboeh · November 22, 2022, 8:21am

We are dealing with two separate issues:

Reaching the web interface. The problem here could be that the DNS of the upstream router (your "modem") returns a local IP which is not forwarded by OpenWrt's DNS by default. This might be fixed by disabling the DNS rebind protection in DNSMasq, but it's safer to add a DNS entry for the modem as stated by @lleachii.
Reaching your Cubieboard. Based on the IP address I assume that it has a static IP address configured and does not use DHCP. If that is the case, you need to add a DNS entry for the Cubieboard as well. In LuCI, this is at Network -> DNS and DHCP -> Hostnames.

@moeller0 I think he can already access the modem's web page, just not using the domain name, only via its IP.

moeller0 · November 22, 2022, 8:43am

Ah, okay I missed that. (And personally I would stop bothering at that point and just use the IP address*, after all "there is no place like 127.0.0.1")

*) IPv4 is simple enough, I do see the attraction of symbolic names once we talk about IPv6 addresses ;).

Bebbi · November 24, 2022, 11:57pm

Good evening,

also in this video https://www.youtube.com/watch?v=L8hchE8z94Y the way is described as in the instructions. But it just does not work for me. If I enter https://192.168.1.5 as IPv4 address as in the video, I get OpenWRT at https://192.168.1.5. PING to 192.168.1.1 is successful. But in the browser there is an error message.

there are so many ways to enter something ...

Bebbi · November 25, 2022, 12:23am

I have downloaded Wireshark. If I understood your work order correctly, the following messages should help:

It doesn't mean much to me. I can find the IP addresses of the PC and modem again in the list.

Yes.

When I try to do that, an error message comes up. "The IP address is outside any DHCP address range".

Thank you for your patience and efforts.

andyboeh · November 25, 2022, 4:34am

Of course, because that's the wrong tab. You are creating a static lease, not a hostname. There is an additional tab called "Hostnames". Here you can add any IP address and its associated hostname - you could also add your "provider.box" here.

NB: If you are not running 22.03, then it's Network -> Hostnames instead.

Bebbi · November 25, 2022, 4:50pm

The result is still that I cannot reach the interface via provider.box and 192.168.1.1.

When I stop the "Modem" interface, I get the error message, "You appear to be connected to the device via the 'Modem' interface. Are you sure you want to shut down this interface?"
I confirmed that. After that, I was able to access the interface via provider.box, but not via IP address.

I'm still confused about https://openwrt.org/docs/guide-user/network/wan/access.modem.through.nat suggesting a way that doesn't work.

But the more important problem is that I can't reach cubieboard2/wiki anymore.

Yesterday I deactivated the firewall software. The Windows firewall is turned off. This did not bring anything.

I can reach provider.box and 192.168.1.1 in the browser from the smartphone via the WLAN. Since then it no longer works from the PC. I can't reach OpenWrt from the smartphone.

andyboeh · November 25, 2022, 5:25pm

We (I) already told you to completely delete the modem interface, and you confirmed that you deleted it. It is useless in your case. You were advised to do so in your other thread over a year ago. If you want to try out things: Do a backup of your OpenWrt router, play around, and restore the backup in case it doesn't work.

The link you posted does not apply because your modem is not in Bridge Mode but in NAT mode.

Via IP, via hostname or both? You should be able to reach it via IP if it is
a) connected to a LAN port and
b) has an IP in the 192.168.2.x range and
c) your computer is also connected to a LAN port.

You should be able to reach it via hostname if you add it to the hostnames section as mentioned before.

Bebbi · November 26, 2022, 2:51am

Good evening,
I did not give any importance to the sentence about the bridge mode. Now I think I understand why the instructions do not fit for me.
I had only set it up again because I wanted to retrace for myself when I could reach the modem and when I couldn't, because I thought that might help me. I should have written that more precisely.

From the smartphone via WLAN I can reach the modem via 192.168.1.1. There I am redirected to provider.box. On the PC only the call via provider.box works.

Since the connection to the Cubieboard has never given any problems so far, I connected a screen. There was indeed an error message when booting. However, I could not fix this yet.